A restructuring paper has been sent to Ministry of Justice staff proposing that 88 jobs be cut within the courts and 51 new positions created.
Public Service Association national secretary Richard Wagstaff says the union knew restructuring was being considered but did not expect so many jobs to go.
He says at a time when the courts are struggling to keep up with backlogs of cases the union cannot support the changes proposed.
A spokesperson for the Ministry says no final decisions have been made, and no frontline staff will be lost.
He says a number of the 88 positions are already vacant and the
Ministry is keen to retain staff whose jobs are disestablished.
Staff have a fortnight to comment on the proposal.